Cross-machine direction embossing of absorbent paper products having an undulatory structure including ridges extending in the machine direction

ABSTRACT

A method of embossing an absorbent web with a machine direction undulatory structure is described. The web has a plurality of ridges extending in its machine direction occurring at a frequency, F, across the web and the method includes providing the web to an embossing station where the web is embossed between a first and second embossing roll, each of which rolls may be provided with a plurality of embossing elements configured to define a plurality of embossing nips. At least a portion of the embossing nips are substantially oriented in a cross-machine direction with respect to the web and have a cross direction length, L. The product F×L is from about 0.1 to about 5.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/235,197, (Attorney Docket No. 2241-A) entitled“Single-Ply Embossed Absorbent Paper Products” filed Sep. 5, 2002, nowabandoned, which was a continuation application of U.S. patentapplication Ser. No. 09/709,185 (Attorney Docket No. 2241) entitled“Single-Ply Embossed Absorbent Paper Products”, filed Nov. 9, 2000, nowU.S. Pat. No. 6,455,129, which was based upon U.S. Provisional PatentApplication No. 60/165,080, of the same title, filed Nov. 12, 1999. Thisapplication is also a continuation-in-part of U.S. patent applicationSer. No. 10/036,770, entitled “An Apparatus and Method for Degrading aWeb in the Machine Direction While Preserving Cross-machine DirectionStrength”, (Attorney Docket No. 2327), filed Dec. 21, 2001. Thepriorities of the foregoing applications are hereby claimed.

BACKGROUND OF THE INVENTION

[0002] Embossing is carried out by passing a web between two or moreembossing rolls, at least one of which carries the desired embosspattern. Known embossing configurations include rigid-to-resilientembossing and rigid-to-rigid embossing. In a rigid-to-resilientembossing system, a single or multi-ply substrate is passed through anip formed between a roll whose substantially rigid surface contains theembossing pattern as a multiplicity of protuberances and/or depressionsarranged in an aesthetically-pleasing manner, and a second roll, whosesubstantially resilient surface can be either smooth or also contain amultiplicity of protuberances and/or depressions which cooperate withthe rigid surfaced patterned roll. Commonly, rigid rolls are formed witha steel body which is either directly engraved upon or which can containa hard rubber-covered, or other suitable polymer, surface (directlycoated or sleeved) upon which the embossing pattern is formed by anyconvenient method such as, for example, being laser engraved. Theresilient roll may consist of a steel core provided with a resilientsurface, such as being directly covered or sleeved with a resilientmaterial such as rubber, or other suitable polymer. The rubber coatingmay be either smooth or engraved with a pattern. The pattern on theresilient roll may be either a mated or a non-mated pattern with respectto the pattern carried on the rigid roll.

[0003] In a rigid-to-rigid embossing process, a single-ply or multi-plysubstrate is passed through a nip formed between two substantially rigidrolls. The surfaces of both rolls contain the pattern to be embossed asa multiplicity of protuberances and/or depressions arranged into anaesthetically-pleasing manner where the protuberances and/or depressionsin the second roll cooperate with those patterned in the first rigidroll. The first rigid roll may be formed, for example, with a steel bodywhich is either directly engraved upon or which can contain a hardrubber-covered, or other suitable polymer, surface (directly coated orsleeved) upon which the embossing pattern is engraved by anyconventional method, such as by laser engraving. The second rigid rollcan be formed with a steel body or can contain a hard rubber covered, orother suitable polymer, surface (directly coated or sleeved) upon whichany convenient pattern, such as a matching or mated pattern, isconventionally engraved or laser-engraved. In perforate embossing, arigid-to-rigid embossing system is typically used. However, arigid-resilient configuration can also be used for perforate embossing.In a related operation, normally referred to as “Dry Marking”, thepattern is formed by protrusions on one roll which compress the sheetagainst an anvil roll which is normally smooth surfaced.

[0004] In perforate embossing the embossing elements are configured suchthat at least a portion of the web located between the embossingelements is perforated. As used herein, generally the terminology“perforated”, “perforate” and the like refers to the existence of either(1) a macro-scale through aperture in the web or (2) when a macro-scalethrough aperture does not exist, at least incipient tearing such aswould increase the transmittivity of light through a small region of theweb or would decrease the machine direction strength of a web by atleast 15% for a given range of embossing depths. When the degree ofincipient tearing is controlled such that the loss of MD strength isless than about 15% but increased transmittivity is obtained, we preferthat the loss of MD strength is at least about 10%. In many cases, itwill be advantageous to perf-emboss heavily such that the MD tensilestrength is decreased about 35% to about 65%.

[0005] Commonly absorbent products such as tissue or towel are subjectedto various combinations of both calendering and embossing to bring thesoftness and bulk parameters into acceptable ranges for premium qualityproducts. Calendering adversely affects bulk and may raise tensilemodulus, which is inversely related to tissue softness. Embossingincreases product caliper (bulk) and can reduce modulus, but lowersstrength and can have a deleterious effect on surface softness.Accordingly, it can be appreciated that these processes can have bothbeneficial and adverse effects on strength, appearance, surfacesmoothness and particularly thickness perception since there is afundamental conflict between bulk and calendering.

[0006] Cross-machine direction (CD) tensile strength and stretch can beassociated with consumer preference for absorbent paper products such aspaper toweling. In particular, consumers prefer a strong, yet balanced,towel of which cross-machine direction (CD) strength and stretch andmachine direction strength and stretch are components. Becauseun-embossed basesheet is typically much stronger and has more stretch inthe machine direction than the cross-machine direction, an embossingprocess which does not lead to excessive losses in cross-machinedirection tensile strength or stretch is desirable for absorbent sheetand more particularly for sheet which has machine direction ridges asdescribed herein.

[0007] In some through air (TAD) processes, an overall pattern isimparted to the web during the forming and drying process by use of apatterned fabric having designs to enhance appearance, cross directionstretch and to balance properties. Such features may include ridgesextending in the machine direction. Through air dried tissues can bedeficient in surface smoothness and softness unless strategies such ascalendering, embossing, chemical softeners and stratification of lowcoarseness fibers on the tissue's outer layers are typically employed inaddition to creping.

[0008] In U.S. Pat. Nos. 5,656,134; 5,690,788; 5,685,954; 6,096,168; and5,885,415 to Marinack et al. (hereinafter the Marinack et al. patents),the disclosure of which is incorporated by reference it was shown thatpaper products having highly desirable bulk, appearance (includingreflectivity) and softness characteristics, can be produced by a processsimilar to conventional wet-press (CWP) processes by replacing theconventional creping blade with an undulatory creping blade having amultiplicity of serrulated creping sections presenting differentiatedcreping and rake angles to the sheet. Further, in addition to impartingdesirable initial characteristics directly to the sheet, the process ofthe Marinack et al. patents produces a sheet which is more capable ofwithstanding calendering without excessive degradation than aconventional wet pressed tissue web.

[0009] The process and apparatus of the Marinack et al. patents makes itpossible to achieve surprisingly high absorbency in a relativelynon-bulky towel thus providing an important new benefit. Similarly, websmade by way of undulatory creping can be calendered more heavily thanmany conventional webs while still retaining bulk and absorbency, makingit possible to provide smoother, and thereby softer feeling surfaceswithout unduly increasing tensile modulus or unduly degrading bulk. Onthe other hand, if the primary goal is to save on the cost of rawmaterials, the tissue of the Marinack et al. patents can have surprisingbulk at a low basis weight without an excessive sacrifice in strength orat low percent crepe while maintaining high caliper. Creping inaccordance with the Marinack et al. patents creates a machine directionoriented shaped sheet which has higher than normal stretch in directionsother than the machine direction, that is, particularly highcross-direction stretch. Embossing without the desired protocol cannegate the gains realized by using the undulatory creping process and/orthe benefits of molded-in machine direction ridges in the web. There isprovided in accordance with the present invention creping protocols andproducts which enhance properties while preserving the benefits impartedto the web during its manufacture by incorporating ridges extending inthe machine direction.

SUMMARY OF THE INVENTION

[0010] A method of embossing an absorbent web with an undulatorystructure having a plurality of ridges extending in the machinedirection occurring at a frequency, F, includes providing the web to anembossing station and embossing the web at the embossing station betweena first and second embossing roll, at least one of which rolls isprovided with a plurality of embossing elements and the rolls arethereby configured to define a plurality of embossing nips therebetween.At least a portion of the embossing nips defined by the embossingelements are substantially oriented in a cross-machine direction withrespect to the web and have a cross direction length, L, and the productF×L is from about 0.1 to about 5. Generally, the product F×L is fromabout 0.2 to about 3 or from about 0.3 to about 2. In preferred cases,the product F×L is from about 0.5 to about 1.5.

[0011] Substantially all of the embossing nips may be substantiallyoriented in the cross-machine direction and may comprise perforateembossing nips. Typically, at least a portion of the embossing elementsare male elements which are perhaps most preferably substantially ovalshaped but may be substantially hexagonal shaped or substantiallyrectangular shaped. The cross-machine direction embossing nips aregenerally at an angle of from about 60° to about 120° from the machinedirection, with an angle of from about 85° to about 95° from the machinedirection being somewhat typical. Generally, at least a portion of thecross-machine direction embossing elements are male elements having aheight of at least about 15 mils; more typically, at least a portion ofthe cross-machine direction embossing elements are male elements havinga height of at least about 30 mils. Various alignment patterns of theelements may be employed, for instance, sometimes the cross-machinedirection embossing elements are in full-step alignment, while in othercases the cross-machine direction embossing elements are in half-stepalignment or in quarter-step alignment.

[0012] Generally, the cross-machine embossing element engagement is ofat least about 15 mils with from about 16 to about 24 or 32 mils beingsomewhat typical. In preferred cases, the cross-machine directionembossing elements have angled sidewalls, wherein the sidewalls have anangle of less than about 20°.

[0013] Perhaps most preferably, the web is a creped web prepared with anundulatory creping blade, having a biaxially undulatory structure withcrepe bars extending in the cross direction and ridges extending in themachine direction. In these embodiments, the web generally has fromabout 4 to about 50 ridges per inch extending in the machine directionwith from about 8 to about 25 ridges per inch extending in the machinedirection being somewhat typical. Preferably, there are from about 10 toabout 16 ridges per inch extending in the machine direction. Thestructure includes crepe bars, that is, the web may have from about 4 toabout 50 ridges per inch extending in the machine direction and fromabout 10 to about 150 crepe bars per inch extending in the cross-machinedirection of the web.

[0014] In some preferred cases, the embossing nips oriented in thecross-machine direction comprise perforate embossing nips and theembossing step is operative to reduce the dry tensile ratio of the weband/or the wet tensile ratio of the web. So also, in general at least aportion of the embossing nips oriented in the cross-machine directionmay be perforate embossing nips such that the process of embossing theweb is operative to increase the transluminance ratio of the web.

[0015] In another aspect of the invention, there is provided a method ofembossing an absorbent web with an undulatory structure extending in themachine direction comprising: providing a web with a plurality of ridgesextending in its machine direction to an embossing station; wherein theplurality of ridges extending the machine direction of the web occur ata frequency, F, across the web; and embossing the web at the embossingstation between a first and second embossing roll, at least one of whichrolls is provided with a plurality of embossing elements and the rollsare thereby configured to define a plurality of embossing nips, whereinat least a portion of the embossing nips defined by the embossingelements are substantially oriented in the cross-machine direction,having a cross direction length, L, and are laterally spaced at adistance, D, with the proviso that the product F×L is between about 0.1and about 5 or the product F×D is between about 0.1 and about 5. Morepreferably, F×L is between about 0.2 and 3 and F×D is between about 0.2and 3. Still more preferably, F×L is between about 0.3 and about 2and/or F×D is between about 0.35 and 2.5.

[0016] The inventive method may operate to reduce MD dry tensile fromabout 35-65% in some cases, while in others less than 15%. When MD drytensile is reduced less than 15%, a reduction of at least about 10% istypical. It is preferred that the embossing method of the inventionreduces the CD dry tensile of a basesheet by less than about 30% andeven more preferably less than about 20%-25% or less than about 15% inespecially preferred embodiments as seen in Table 5.

[0017] Caliper gains of 15%, 20%, 25%, 30%, 40% and more are seen withthe products of the invention as compared with the unembossed basesheetfrom which they were made.

[0018] In still yet another aspect of the invention, there is providedan embossed absorbent web having an undulatory structure extending inthe machine direction and a plurality of embossments wherein theundulatory structure of the web comprises a plurality of ridgesextending in the machine direction of the web occurring at a frequency,F, across the web and at least a portion of the embossments extendsubstantially in the cross-machine direction. The embossments extendingin the cross-machine direction extend in the cross-machine direction adistance, L′; and the embossments extending in the cross-machinedirection are laterally spaced from adjacent design elements a distance,D′; with the proviso that the product F×L′ is between about 0.1 and 5 orthe product F×D′ is between about 0.1 and 5. More preferably, F×L′ isbetween about 0.2 and 3 and F×D′ is also between about 0.2 and 3. Stillmore preferably, F×L′ is between about 0.3 and about 2 and/or F×D′ isbetween about 0.35 and 2.5. Preferably, the web has a dry tensile ratioof less than about 1.2 and a transluminance ratio of at least about1.005. A transluminance ratio of at least about 1.01 is desirable inmany cases.

[0019] In some preferred cases, substantially all of the embossedregions are substantially oriented in the cross-machine direction.

BRIEF DESCRIPTION OF THE INVENTION

[0020] The invention is described in detail below wherein like numeralsand letters indicate like features and wherein:

[0021]FIG. 1 is a graph of embossment depth versus MD tensile loss;machine direction and cross-machine direction when using rigid toresilient embossing as compared to perforate embossing a web as in FIG.2D.

[0022]FIG. 3A is a schematic diagram illustrating embossing a web withembossing rolls having cross-direction embossing elements in accordancewith the invention;

[0023]FIG. 3B is an enlarged top schematic view of an embossing roll ofFIG. 3A;

[0024]FIG. 3C is an enlarged schematic view from the cross-machinedirection of an embossing roll of FIG. 3A;

[0025]FIG. 3D is an enlarged schematic view from the machine directionof an embossing roll of FIG. 3A;

[0026]FIG. 4 illustrates cross-machine direction elements according toanother embodiment of the present invention;

[0027]FIG. 5 illustrates cross-machine direction elements according toanother embodiment of the present invention;

[0028] FIGS. 6A-6C are schematic side views of the cross-machinedirection elements of embodiments of the present invention havingdiffering wall angles and illustrating the effect of the differing wallangles;

[0029] FIGS. 7A-7C are schematic side views of the cross-machinedirection elements of embodiments of the present invention havingdiffering wall angles and illustrating the effect of the differing wallangles;

[0030] FIGS. 8A-8C are schematic side views of the cross-machinedirection elements of yet another embodiment of the present inventionhaving differing wall angles and illustrating the effect of thediffering wall angles;

[0031]FIGS. 9 and 10 are plots of element clearance vs. embossengagement illustrating picking tendencies and conditions;

[0032]FIG. 11 illustrates the alignment of the cross-machine directionelements according to an embodiment of the present invention;

[0033]FIG. 12 illustrates the alignment of the cross-machine directionelements according to another embodiment of the present invention;

[0034]FIG. 13 illustrates the alignment of the cross-machine directionelements according to another embodiment of the present invention;

[0035]FIG. 14 illustrates the alignment of the cross-machine directionelements according to yet another embodiment of the present invention;

[0036] FIGS. 15A-15B illustrate embossing rolls having bothcross-machine direction and machine direction elements according to anembodiment of the present invention;

[0037]FIG. 16 illustrates the effect of cross-machine direction elementson a web according to yet another embodiment of the present invention;

[0038]FIG. 17 illustrates the effect of cross-machine direction elementson a web according to yet another embodiment of the present invention;

[0039]FIG. 18 depicts a transluminance test apparatus;

[0040]FIG. 19 is a schematic diagram of a papermachine useful for makinga web with MD ridges;

[0041]FIG. 20 is a schematic diagram illustrating creping angles forproducing a creped web which may be embossed in accordance with theinvention;

[0042] FIGS. 21A-21D illustrate an undulatory creping blade which may beused to produce a creped biaxially undulatory web shown in FIG. 21Ewhich may be embossed in accordance with the invention;

[0043]FIG. 22 is a schematic diagram of a drying apparatus which may beused to dry a wet-creped web;

[0044]FIG. 23 is a diagram of another drying apparatus which may be usedto dry a wet-creped web; and

[0045]FIG. 24 is a schematic illustration of a portion of an embossedsheet of the invention.

DETAILED DESCRIPTION

[0046] Reference will now be made in detail to preferred embodiments ofthe present invention, examples of which are illustrated in theaccompanying drawings.

[0047] The present invention can be used to emboss a variety of types ofcellulosic webs. The webs can be continuous or of a fixed length.Moreover, embossed webs can be used to produce any are recognizedproduct, including, but not limited to, paper towels, napkins, tissue,or the like. The product can be a single ply or a multiply paperproduct, or a laminated paper product having multiple plies. Inaddition, the present invention can be used with a web made from virginfurnish, recycled furnish, or a web containing both virgin and recycledfurnish, synthetic fibers, or any combination thereof.

[0048] The absorbent sheet may be a tissue product having a basis weightof from about 5 to about 25 pounds per 3,000 square foot ream, or atowel product having a basis weight of from about 10 to about 40 poundsper 3,000 square foot ream. In any case, the sheet may be preparedutilizing recycle furnish.

[0049] In accordance with the invention, as broadly described, theconverting process includes an embossing system of at least twoembossing rolls, the embossing rolls defining at least one nip throughwhich a web to be embossed is passed. The embossing elements may bepatterned to create perforations in the web as it is passed through thenip. Perforations are created when the strength of the web is locallydegraded between two bypassing embossing elements resulting in either(1) a macro scale through-aperture or (2) in those cases where a macroscale through-aperture is not present, at least incipient tearing, wheresuch tearing would increase the tansmittivity of light through a smallregion of the web or would decrease the machine direction strength of aweb by at least 15% for a given range of embossing depths. FIG. 1depicts a comparison of the effects on reduction of strength in themachine direction when perforate embossing a web, as defined herein, andnon-perforate embossing a web. In particular, a conventional wet pressedbasesheet was perforate embossed between two steel rolls. The samebasesheet was non-perforate embossed in a rubber to steel configuration.In addition, a through-air-dried basesheet was also perforate andnon-perforate embossed. The reduction in machine direction strength wasmeasured for each of the sheets and the results are plotted on FIG. 1.

[0050] As shown in FIG. 1, when non-perforate embossing either a CWP orTAD web to depths of up to 40 mils, the reduction of paper strength inthe machine direction is less than 5%. And, when non-perforate embossingeither of the CWP or TAD webs at a depth of 80 mils, the reduction ofstrength of the web is less than 15%. When perforate embossing a web asdisclosed in this invention, a greater reduction in strength of the webcan be achieved. In the example set forth herein, strength reductions ofgreater than 15% are achieved when perforate embossing at depths of atleast about 15 mils as compared to rubber to steel embossing which canresult in these strength losses at emboss depths of over 60 mils.Accordingly, for present purposes, perforation is specifically definedas locally degrading the strength of the web between two bypassingembossing elements resulting in either (1) the formation of a macroscale through-aperture or (2) when a macro scale through-aperture is notformed, at least incipient tearing, where such tearing would eitherincrease the transmittivity of light through a small region of the webor would decrease the machine direction strength of a web by at leastthe percentages set forth in FIG. 1, wherein the “at least” percentagesare indicated by the dashed line.

[0051] Not being bound by theory, we believe that the superior strengthreduction results achieved in some embodiments of the present inventionare due to the location of the local degradation of the web whenperforate embossing as compared to when non-perforate embossing. When aweb is embossed, either by perforate or non-perforate methods, theportion of the web subject to the perforate or non-perforate nip isdegraded. In particular, as a web passes through a non-perforate nip forembossing, the web is stressed between the two embossing surfaces suchthat the fiber bonds are stretched and sometimes, when the web is overembossed, which is not desired when non-perforate embossing a web, thebonds are torn or broken. When a web is passed through a perforate nip,the web fiber bonds are at least incipiently torn by the stresses causedby the two bypassing perforate elements. As stated above, however, onedifference between the two methods appears to be in the location of atleast incipient tearing.

[0052] When a web is over-embossed in a rubber to steel configuration,the male steel embossing elements apply pressure to the web and therubber roll, causing the rubber to deflect away from the pressure, whilethe rubber also pushes back. As the male embossing elements roll acrossthe rubber roll during the embossing process, the male elements pressthe web into the rubber roll which causes tension in the web at the areaof the web located at the top edges of the deflected rubber roll, i.e.,at the areas at the base of the male embossing elements. When the web isover-embossed, tearing can occur at these high-tension areas. Moreparticularly, FIGS. 2A-2C depicts rubber to steel embossing of a web atvarious embossing depths. FIG. 2A depicts embossing of a web atapproximately 0 mils. In this configuration the rubber roll pins the webat the points where the web contacts the steel roll elements tops.Typically no tearing will occur in this configuration. In FIG. 2B, wherethe embossing depth is approximately the height of the steel embossingelement, the web is pinned at the element tops and at a point betweenthe bases of the adjacent steel elements. As with the configurationdepicted in FIG. 2B, tearing does not typically occur in thisconfiguration for conventional embossing procedures. FIG. 2C depicts anembossing depth comparable to or greater than the height of the steelelement. In this configuration, the “free span” of the web, i.e., thesections of the web that are not pinned between the rubber and steelrolls, becomes shorter as the rubber material fills the area between theadjacent elements. When web rupturing occurs, it tends to occur near thelast location where web movement is possible; that is, the area ofdegradation 40 is the last area that is filled by the rubber material,namely the corners where the bases of the elements meet the surface ofthe emboss roll.

[0053] When a web is perforate embossed, on the other hand, the areas ofdegradation 42, as shown in FIG. 2D, are located along the sides of theperforate embossing elements in embossing nip 41. It appears that as aresult of this difference the degradation of the web and the resultantreduction of web strength is dramatically different.

[0054] In one embodiment according to the present invention, theembossing rolls have substantially identical embossing element patterns,with at least a portion of the embossing elements configured such thatthey are capable of producing perforating nips which are capable ofperforating the web. As the web is passed through the nip, an embossingpattern is imparted on the web. It is preferred that the embossing rollsbe either steel or hard rubber, or other suitable polymer. The directionof travel of the web as it passes through the nip is referred to as themachine direction shown in the various Figures as MD 35. The transversedirection of the web that spans the emboss roll is referred to as thecross-machine direction and is referred to as CD 37. It is furtherpreferred that a predominant number, i.e., at least 50% or more, of theperforations are configured to be oriented such that the major axis ofthe perforation is substantially oriented in the cross-machinedirection. An embossing nip is substantially oriented in thecross-machine direction if the nip is at an angle of from about 60° to120° from the machine direction of the web.

[0055] In an embodiment according to the present invention, and as shownin FIG. 3A, the converting process includes an embossing station 20including embossing rolls 22 defining generally a nip 28 (which includesa plurality of nips 41 as shown in FIGS. 4 and 5) through which the web,W, to be embossed is passed. According to one embodiment, the embossingrolls 22 are matched embossing rolls. The embossing rolls can be, forexample, either steel or hard rubber, or other suitable polymer. Theembossing rolls 22 have at least a portion of embossing elements 34oriented such that the major axes of the elements 34 are in thecross-machine direction 37, i.e., the elements are in the cross-machinedirection. Cross direction 37 is perpendicular to or 90° offset from MD35. It is possible to envisage configurations in which perforationsextending in the cross-machine direction are formed by elements whichare longer in the machine direction 35, although such a configurationwould normally be sub-optimal as it would compromise the overall numberof perforations which could be formed in the web. Accordingly, when wediscuss elements that are configured such that the orientation of theperforation formed by those elements extends in the cross-machinedirection, that should be understood to be irrespective of the shape ofthe portions of the element that do not contribute to the shape of thenip, whether the element be male or female. While the embossing rolls 22can also have embossing elements oriented such that the major 20 axis ofthe elements is in the machine direction, a predominant number, i.e., atleast 50% or more, of the elements 34 should be oriented such that theyare capable of producing perforating nips extending in the cross-machinedirection. In another embodiment, substantially all, i.e., at least morethan 75%, of the elements 34 are oriented such that they are capable ofproducing perforating nips extending in the cross-machine direction. Inyet another embodiment, all of the elements are oriented in thecross-machine direction. Moreover, at least about 25% of thecross-machine direction elements are perforating elements. In apreferred embodiment, all of the cross-machine direction elements areperforating elements. Thus, when the web passes through the embossingrolls 22, at least a portion of the cross-machine direction elements arealigned such that the web is perforated such that at least a portion ofthe perforations are substantially oriented in the cross-machinedirection.

[0056] The end product characteristics of a cross-machine directionperforated embossed product can depend upon a variety of factors of theembossing elements that are imparting a pattern on the web. Thesefactors can include one or more of the following: embossing elementheight, angle, shape, including sidewall angle, spacing, engagement, andalignment, as well as the physical properties of the rolls, basesheet,and other factors. Following is a discussion of a number of thesefactors.

[0057] An individual embossing element 34 has certain physicalproperties, such as height, angle, and shape, that affect the embossingpattern during an embossing process. The embossing element can be eithera male embossing element or a female embossing element. The height H ofan element 34 is the distance the element 34 protrudes from the surfaceof the embossing roll 22. It is preferred that the embossing elements 34have a height of at least about 15 mils. In one embodiment according tothe present invention, the cross-machine direction elements 34 have aheight of at least about 30 mils. In another embodiment of the presentinvention, the cross-machine direction elements 34 have a height ofgreater than about 45 mils. In yet another embodiment of the invention,the cross-machine elements have a height of greater than about 60 mils.In yet another embodiment, a plurality of the elements 34 on the rollwill not have planar tops but rather will have at least two regions, afirst region having a first height, H, and at least a second regionhaving a second height, H′. Preferably, the contours of the surfaces arechosen as hereinafter described with bevels and radii to avoidunintended disruptions. In a preferred embodiment, the elements 34 havea height, H, of between about 30 to 65 mils. Those of ordinary skill inthe art will understand that there are a variety of element heights thatcan be used, depending upon a variety of factors, such as the type ofweb being embossed and the desired end product.

[0058] The angle of the cross-machine direction elements 34substantially defines the direction of the degradation of the web due tocross-machine perforate embossing. When the elements 34 are oriented atan angle of about 90° from the machine direction as shown in FIG. 3B,i.e., in the absolute cross-machine direction, the perforation of theweb can be substantially in the direction of about 90° from the machinedirection and, thus, the degradation of the web strength issubstantially in the machine direction. On the other hand, when theelements 34 are oriented at an angle from the absolute cross-machinedirection, degradation of strength in the machine direction will be lessand degradation of strength in the cross-machine direction will be moreas compared to a system where the elements 34 are in the absolutecross-machine direction.

[0059] The angle of the elements 34 can be selected based on the desiredproperties of the end product. Thus, the selected angle can be any anglethat results in the desired end product. In an embodiment according tothe present invention, the cross-machine direction elements 34 can beoriented at an angle of at least about 60° from the machine direction ofthe web and less than about 120° from the machine direction of the webto define an embossing nip of like orientation. In another embodiment,the cross-machine directions element 34 are oriented at an angle from atleast about 75° from the machine direction of the web and less thanabout 105° from the machine direction of the web. In yet anotherembodiment, the cross-machine direction elements 34 are oriented at anangle from at least about 80° from the machine direction of the web andless than about 100° from the machine direction of the web. In apreferred embodiment, the cross-machine direction elements 34 areoriented at an angle of about 85-95° from the machine direction.Generally speaking, the embossing elements have a cross-directionlength, 52, and a machine direction width, 50. If the elements areoffset from the MD and/or CD by an angle, distance 52, and 50 arerespectively taken as the distance the element extends along the CD orMD, respectively. Note that the embossing elements are spaced a lateraldistance, 54, as shown in FIG. 3B. Distance 54 may be, for example,0.015 inches or so while distance 52 may be from about 50 to 150 milswhen embossing a sheet with 12-16 MD ridges per inch.

[0060] A variety of element shapes can be successfully used in thepresent invention. The element shape is the “footprint” of the topsurface of the element, as well as the side profile of the element. Itis preferred that the elements 34 have a length (in the cross-machinedirection/width (in the machine direction) (i.e., distance 52/distance50) aspect ratio of at least greater than 1.0, however while noted aboveas sub-optimal, the elements 34 can have an aspect ratio of less than1.0. It is further preferred that an aspect ratio be about 3.5, and inmany preferred cases greater than about 1.5. One element shape that canbe used in this invention is a hexagonal element, as depicted in FIG. 4.Another element shape, termed an oval, is depicted in FIG. 5. For ovalelements, it is preferred that the ends have radii of at least about0.003″ and less than about 0.030″ for at least the side of the elementforming a perforate nip 41. In one embodiment, the end radii are about0.0135″. Those of ordinary skill in the art will understand that avariety of different embossing element shapes, such as rectangular, canbe employed to vary the embossing pattern. For convenience, opposedmatched elements forming on embossing nip are sometimes shown ashatched. It should be appreciated that embossing nips are formed betweenadjacent hatched and unhatched elements in the schematic diagramsshowing the embossing elements.

[0061] In one embodiment, at least a portion of the elements 34 arebeveled. In particular, in one embodiment the ends of a portion of theelements 34 are beveled. Oval elements with beveled edges are depictedin FIGS. 3A-3D. By beveling the edges, the disruptions caused by theembossing elements can be better directed in the cross-machinedirection, thereby reducing cross-machine direction degradation causedby the unintentional machine direction disruptions. The bevel dimensionscan be from at least abut 0.010″ to at least about 0.025″ long in thecross-machine direction and from at least about 0.005″ to at least about0.015″ in the z-direction. Other elements, such as hexagonal elements,can be beveled, as well.

[0062] The cross-machine direction sidewall of the elements 34 definesthe cutting edge of the elements 34. According to one embodiment of thepresent invention, the cross-machine direction and machine directionsidewalls of the elements 34 are angled in as seen in FIGS. 3A-3D. Assuch, when the cross-machine direction sidewalls are angled, the base ofthe element 34 has a width, that is larger than that of the top of theelement. It is preferred that the cross-machine direction sidewall anglebe less than about 20°. It is further preferred that the cross-machinedirection sidewall angle be less than about 17°. It is still furtherpreferred that the cross-machine direction sidewall angle be less thanabout 14°. Finally, in a preferred embodiment the cross-machinedirection sidewall angle is less than about 11°. It is further preferredthat the cross-machine direction sidewall angle be between about 7° and11°. The cross direction sidewall angle, θ, is measured from aperpendicular to the embossing roll surface.

[0063] When the opposing elements 34 of the embossing rolls are engagedwith each other during an embossing process, the effect on the web isimpacted by at least element spacing, engagement, and alignment. Whenperforate embossing, the elements 34 are spaced such that the clearancebetween the sidewalls of elements of a pair, i.e., one element 34 fromeach of the opposing embossing rolls 22, creates a nip 41 thatperforates the web as it is passed through the embossing rolls 22. Ifthe clearance between elements 34 on opposing rolls is too great, thedesired perforation of the web may not occur. On the other hand, if theclearance between elements 34 is too little, the physical properties ofthe finished product may be degraded excessively or the embossingelements themselves could be damaged. The required level of engagementof the embossing rolls is at least a function of the embossing pattern(element array, sidewall angle, and element height), and the basesheetproperties, e.g., basis weight, caliper, strength, and stretch. At aminimum, it is preferred that the clearances between the sidewalls ofthe opposing elements of the element pair be sufficient to avoidinterference between the elements. In one embodiment, the minimumclearance is about a large fraction of the thickness of the basesheet.For example, if a conventional wet press (CWP) basesheet having athickness of 4 mils is being embossed, the clearance can be at leastabout 2-3 mils. If the basesheet is formed by a process which results ina web with rather more bulk, such as, for example, a through air dried(TAD) method or by use of an undulatory creping blade, the clearancecould desirably be relatively less. Those of ordinary skill in the artwill be able to determine the desired element spacing of the presentinvention based on the factors discussed above using the principles andexamples discussed further herein.

[0064] As noted above, in one embodiment it is preferred that the heightof the elements 34 be at least about 30 mils, and it is furtherpreferred that the height be from about 30 to 65 mils. Engagement, asused herein, is the overlap in the z-direction of the elements fromopposing embossing rolls when they are engaged to form a perforatingnip. The engagement overlap should be at least 1 mil.

[0065] In one embodiment, the engagement 39 is at least about 15 mils.Various engagements are depicted in FIGS. 6A-8C. In particular, FIGS.6A-6C depict a 32 mil engagement. That is, the overlap of the elements,in the z-direction, is 32 mils. The desired engagement is determined bya variety of factors, including element height, element sidewall angle,element spacing, desired effect of the embossing elements on thebasesheet, and the basesheet properties, e.g., basis weight, caliper,strength, and stretch. Those of ordinary skill in the art willunderstand that a variety of engagements can be employed based on theabove, as well as other factors. It is preferred that the engagement bechosen to substantially degrade the machine direction tensile strengthof the web. It is further preferred that the engagement be at least 5mils.

[0066] Where the element height, H, is about 42.5 mils and the elementshave sidewall angles of from about 7° to 11°, the engagement range canbe from about 16 to 32 mils. FIGS. 6A-6C depicts a 32 mil engagement,where the element heights are 42.5 mils and the sidewall angles arerespectively 7°, 9°, and 11°. It is believed that lower sidewall anglesmake the process significantly easier to run with more controllabilityand decreased tendency to “picking”.

[0067] Picking is the occurrence of fiber being left on the embossingroll or rolls as the web is embossed. Fiber on the roll can diminish therunability of the process for embossing the web, thereby interferingwith embossing performance. When the performance of the embossing rollsis diminished to the point that the end product is not acceptable or therolls are being damaged, it is necessary to stop the embossing processso that the embossing rolls can be cleaned. With any embossing process,there is normally a small amount of fiber left on the roll which doesnot interfere with the process if the roll is inspected periodically,e.g., weekly, and cleaned, if necessary. For purposes of the invention,we define picking as the deposition of fiber on the rolls at a rate thatwould require shut down for cleaning of the rolls more frequently thanonce a week.

[0068] The following examples exhibit the occurrence of picking observedin certain arrangements of cross-machine direction perforate embossedpatterns. This data was generated during trials using steel embossingrolls engraved with the cross-machine direction beveled oval embossingpattern at three different sidewall angles. In particular, the embossingrolls were engraved with three separate regions on the rolls—a 7°embossing pattern, a 9° embossing pattern, and an 11° embossing pattern.Two trials were performed. In the first trial, the embossing rolls hadan element height, H, of 45 mils. The basesheet, having a thickness of6.4 mils, was embossed at engagements of 16, 24, and 32 mils. In thesecond trial, the steel rolls were modified by grinding 2.5 mils off thetops of the embossing elements, thereby reducing the element height to42.5 mils and increasing the surface area of the element tops. Thebasesheet having a thickness of 6.2 mils was embossed at engagements of16, 24, 28 and 32 mils. For each trial, embossing was performed in bothhalf step and full step alignment.

[0069] The element clearances for each of the sidewall angles of thefirst and second trials have been plotted against embossing engagementin FIGS. 9 and 10, respectively. The broken horizontal line on each plotindicates the caliper of a single ply of the basesheet that wasembossed. The graphs have been annotated to show whether fiber pickingwas observed at each of the trial conditions (half step observationbeing to the left of the slash, full step observation to the right). Thepicking results are depicted in FIGS. 9 and 10, below.

[0070]FIG. 9 shows that for this particular trial using embossing rollshaving a 45 mil element height, picking did not occur at any of thesidewall angles. However, as shown in FIG. 10, when the embossing rollshaving a 42.5 mil element height were run, fiber picking was observed onthe 11° sidewall angle elements at the higher embossing engagements,i.e., 24, 28, and 32 mils. No fiber picking was encountered withelements having sidewall angles of 7° or 9°.

[0071] Based on the observed data, it appears that picking is a functionof the element height, engagement, spacing, clearance, sidewall angle,alignment, and the particular physical properties of the basesheet,including basesheet caliper. An example of element clearance 43 can beseen in FIGS. 6A-6C, where the side profiles of the 42.5 mil elements(having 7°, 9°, and 11° sidewall angles) at 32 mil embossing engagementas shown. Clearance is the distance between adjacent engaging embossingelements. As noted above, the caliper of the embossed sheet for thistrial was 6.2 mils. For the configuration shown in FIG. 6A, thecalculated or theoretical clearance at 7° is 0.004906″ (4.906 mils), theclearance at 9° is 0.003911″ (3.911 mils), and the clearance at 11° is0.00311″ (3.11 mils) (FIG. 6B). Thus, for this trial at a 32 milengagement, picking was observed only when the clearance was less thanabout ½ of the caliper of the sheet. Compare this to the clearance forthe configuration shown in FIGS. 7A-7C. FIGS. 7A-7C depict the sidewallprofiles of the 42.5 mil elements at 28 mil embossing engagement. Inthis arrangement, the calculated or theoretical clearance at 7° is0.006535″ (6.535 mils) (FIG. 7A), the clearance at 9° is 0.005540″(5.540 mils) (FIG. 7B), and the clearance at 11° is 0.004745″ (4.745mils) (FIG. 7C). In this trial, picking was observed when the clearance43 was less than about ¾ of the caliper of the sheet. Note, however,that when embossing at 32 mils, as described above, picking did notoccur at 9°, while the clearance was less than 4.745 mils. FIGS. 8A-8Cdepict the sidewall profiles of the 42.5 mil elements at 24 milengagement. In this arrangement, the clearance at 11°is 00.005599″(5.599 mils) (FIG. 8C), slightly less than the caliper of the sheet. Asshown in FIG. 10, picking did occur for these elements, but only whenthe elements were in full step alignment and not when in half stepalignment. And, as shown in FIG. 10, picking did not occur at all, atany angle, engagement, or alignment, for the roll having elements 45mils in height.

[0072] Thus, based on the collected data, picking can be controlled byvarying element height, engagement, spacing, clearance, alignment,sidewall angle, roll condition, and the physical properties of thebasesheet. Based upon the exemplified information, those of ordinaryskill in the art will understand the effects of the various parametersand will be able to determine the various arrangements that will atleast achieve a non-picking operation, i.e., the configuration requiredto avoid an unacceptable amount of picking based on the factorsdiscussed above, and, hence, produce acceptable paper products with aprocess that does not require excessive downtime for roll cleaning.

[0073] The element alignment affects the degradation of the web in themachine and cross-machine directions. Element alignment refers to thealignment in the cross-machine direction within the embossing elementpairs when the embossing rolls are engaged. FIG. 11 depicts anembodiment including hexagonal embossing elements having a full stepalignment, i.e., where the elements are completely overlapped in thecross-machine direction. FIG. 12 depicts an embodiment wherein hexagonalembossing elements are in half step alignment, i.e., where the elementsof each element pair are staggered so that half of the engaged portionof their cross-machine direction dimensions overlap. FIG. 13 depicts anembodiment wherein hexagonal embossing elements are in quarter stepalignment, i.e., where the elements of each element pair are staggeredso that one quarter of the engaged portion of their cross-machinedirection dimensions overlap. The embodiment depicted in FIG. 14 is astaggered array, wherein each element pair is in half step alignmentwith adjacent element pairs. Those of ordinary skill in the art willunderstand that a variety of element alignments are available for usewith this invention, depending upon preferred embossing patterns, webstrength requirements, and other factors.

[0074] It should further be appreciated from FIGS. 11 and 12 that thenip extends over a length, L, between embossing elements when they areengaged in the embossing position and the nips are then spaced apart alateral or CD distance, D. Generally speaking, L is taken as the CDdistance that the nip extends between two opposed embossing surfacesextending in the CD when the embossing elements are engaged, while D isthe CD distance between adjacent nips along the CD (cross-machinedirection). These parameters are best appreciated by reference to FIGS.11 and 12; however, they may be estimated in many cases by reference tothe corresponding dimensions of the embossing elements on the rolls;that is to say, L extends in the direction of distance 52 in FIGS. 3 andD extends in the direction of distance 54 in FIG. 3 but will differ inactual dimensions when the elements are shaped as shown. When L and/or Dvary over the height of the nip, L and D are determined as follows: L isthe maximum length defined between two opposed CD embossing surfaces andD is the minimum CD distance between embossing nips. Thus, L and D areapproximately equal to L′ and D′ in most cases as discussed inconnection with FIG. 24 below. The inter-relationship between elementgeometry is readily appreciated by reference to FIGS. 3A through 3D. Foropposed elements spaced a distance 54 of 0.015 inches or so, D may varybetween about 0.096 and 0.056 inches or so depending upon engagement.Likewise, for opposed elements having an upper surface with a CD span of0.047 inches and a base CD span 52 of 0.128 inches, L may vary betweenabout 0.047 (0 engagement) and 0.09, which is where the nip is at amaximum at roughly the midpoint of the element heights when so engaged.

[0075] As noted above, the elements can be both in the machine directionand cross-machine direction. FIGS. 15A and 15B depict an emboss rollhaving cross-machine direction and machine direction hexagonal elements.

[0076] In another embodiment, depicted in FIG. 16, beveled oval elementsare in full step alignment. As with the full step hexagonal elementsdiscussed above, in the area between the element pairs perforationsexist primarily in the cross-machine direction. However, between thepairs of element pairs, perforations can be caused in the machinedirection. The result is a degradation of strength in both the machineand cross-machine directions. In the embodiment depicted in FIG. 17, onthe other hand, where the beveled oval elements in a half step alignmentare employed, the machine direction perforations are substantiallyreduced. In particular, between the elements in half step alignment, theperforation lies primarily in the cross-machine direction. Between theelement pairs, which are in zero step alignment, primarily pinpointruptures exist. These pinpoint ruptures have a minor effect ondegradation of the directional properties of the web.

[0077] Those of ordinary skill in the art will understand that numerousdifferent configurations of the above described element parameters,i.e., element shape, element orientation, sidewall angle, spacing,height, engagement, and alignment, can be employed in the presentinvention. The selection of each of these parameters may depend upon thebasesheet used, the desired end product, or a variety of other factors.

[0078] To establish the effectiveness of the various element patterns inperforating the web in the cross-machine direction, and therebydegrading machine direction strength while maintaining cross-machinedirection strength, a test was developed, the transluminance test, toquantify a characteristic of perforated embossed webs that is readilyobserved with the human eye. A perforated embossed web that ispositioned over a light source will exhibit pinpoints of light intransmission when viewed at a low angle and from certain directions. Thedirection from which the sample must be viewed, e.g., machine directionor cross-machine direction, in order to see the light, is dependent uponthe orientation of the embossing elements. Machine direction orientedembossing elements tend to generate machine direction ruptures in theweb which can be primarily seen when viewing the web in thecross-machine direction. Cross-machine direction oriented embossingelements, on the other hand, tend to generate cross-machine directionruptures in the web which can be seen primarily when viewing the web inthe machine direction.

[0079] The transluminance test apparatus, as depicted in FIG. 18,consists of a piece of cylindrical tube 44 that is approximately 8.5″long and cut at a 28° angle. The inside surface of the tube is paintedflat black to minimize the reflection noise in the readings. Lighttransmitted through the web itself, and not through a rupture, is anexample of a non-target light source that could contribute totranslucency noise which could lead other embossed webs to havetransluminance ratios slightly exceeding 1.0, but typically by no morethan about 0.05 points. A detector 46, attached to the non-angled end ofthe pipe, measures the transluminance of the sample. A light table 48,having a translucent glass surface, is the light source.

[0080] The test is performed by placing the sample 50 in the desiredorientation on the light table 48. Detector 46 is placed on top of thesample 50 with the long axis of the tube 44 aligned with the axis of thesample 50, either the machine direction or cross-machine direction, thatis being measured and the reading on a digital illuminometer 52 isrecorded. The sample 50 is turned 90° and the procedure is repeated.This is done two more times until all four views, two in the machinedirection and two in the cross-machine direction, are measured. In orderto reduce variability, all four measurements are taken on the same areaof the sample 50 and the sample 50 is always placed in the same locationon the light table 48. To evaluate the transluminance ratio, the twomachine direction readings are summed and divided by the sum of the twocross-machine direction readings.

[0081] To illustrate the results achieved when perforate embossing withcross-machine direction elements as compared to machine directionelements, a variety of webs were tested according to the above describedtransluminance test. The results of the test are shown in Table 1. TABLE1 Transluminance Ratios Basis Creping Weight Method Emboss EmbossTransluminance (lbs/ream) (Blade) Alignment Pattern Ratio 30 UndulatoryFull Step CD Beveled 1.074 Oval 30 Undulatory Half Step CD Beveled 1.056Oval 32 Undulatory Half Step CD Beveled 1.050 Oval 30 Undulatory HalfStep CD Oval 1.047 31 Undulatory Half Step CD Oval 1.044 31 UndulatoryFull Step CD Oval 1.043 30 Undulatory Full Step CD Beveled 1.040 Oval 32Undulatory Half Step CD Beveled 1.033 Oval 30 Undulatory Half Step CDBeveled 1.033 Oval 30 Undulatory Full Step CD Oval 1.027 32 UndulatoryHalf Step CD Beveled 1.025 Oval 30 Undulatory Half Step CD Oval 1.022 31Undulatory Full Step CD Oval 1.018 20 Undulatory Half Step CD Beveled1.015 Oval 30 Undulatory Half Step CD Beveled 1.012 Oval 30 UndulatoryFull Step CD Beveled 1.006 Oval 28 Standard Unknown MD Perforated 1.00024 Undulatory Half Step MD Perforated 0.988 22 Standard Unknown MDPerforated 0.980 29 Undulatory Half Step MD Perforated 0.966 29Undulatory Half Step MD Perforated 0.951 31 Undulatory Half Step MDPerforated 0.942 29 Undulatory Half Step MD Perforated 0.925

[0082] A transluminance ratio of greater than 1.000 indicates that themajority of the perforations are in the cross-machine direction. Forembossing rolls having cross-machine direction elements, the majority ofthe perforations are in the cross-machine direction. And, for themachine direction perforated webs, the majority of the perforations arein the machine direction. Thus, the transluminance ratio can provide aready method of indicating the predominant orientation of theperforations in the web.

[0083] As noted above, perforated embossing in the cross-machinedirection preserves cross-machine direction tensile strength. Thus,based on the desired end product, a web perforate embossed with across-machine direction pattern will exhibit one of the following whencompared to the same basesheet embossed with a machine directionpattern: (a) a higher cross-machine direction tensile strength atequivalent finished product caliper, or (b) a higher caliper atequivalent finished product cross-machine direction tensile strength.

[0084] Furthermore, the tensile ratio (a comparison of the machinedirection tensile strength to the cross-machine direction tensilestrength—MD strength/CD strength) of the cross-machine perforateembossed web typically will be at or below the tensile ratio of thebasesheet, while the tensile ratio of the sheet embossed using prior artmachine direction perforate embossing typically will be higher than thatof the basesheet. Dry tensile strengths (MD and CD) are measured with astandard Instron test device which may be configured in various ways,using for example, 3-inch wide strips of tissue or towel, conditioned at50% relative humidity and 23° C. (73.4° F.), with the tensile test runat a crosshead speed of 2 in/min. Tensiles are sometimes reported inbreaking length (BL, km). Wet tensile is measured by the Finch cupmethod or following generally the procedure for dry tensile, wet tensileis measured by first drying the specimens at 100° C. or so and thenapplying a 1½ inch band of water across the width of the sample with aPayne Sponge Device prior to tensile measurement. Wet/dry tensile ratiosare simply ratios of the values determined by way of the foregoingmethods.

[0085] Higher cross-machine direction strength at equivalent caliper isdemonstrated in Table 2. This table compares two products perforateembossed from the same basesheet—a 29 pound per ream (lbs/R), undulatoryblade-creped, conventional wet press (CWP) sheet. TABLE 2 Increased CDStrength at Equivalent Caliper MD Dry CD Dry Dry Tensile Emboss BasisWt. Caliper Tensile Tensile Ratio (perforate) (lbs/R) (mils) (g/3″)(g/3″) (MD/CD) CD 29.1 144 3511 3039 1.16 Hexagonal MD 29.2 140 43621688 2.58 Hexagonal

[0086] As shown in Table 2, the cross-machine direction perforateembossed web has approximately the same caliper as the machine directionperforate embossed web (144 vs. 140 mils, respectively), but itscross-machine direction dry tensile strength (3039 g/3″) is considerablyhigher than that of the machine direction hexagonal-embossed web (1688g/3″). In addition, compared to the tensile ratio of the basesheet(1.32, see Table 3, below), the cross-machine direction perforateembossed web has a lower ratio (1.16), while the machine directionperforate embossed web has a higher ratio (2.58). Thus the method of thepresent invention provides a convenient, low cost way of “squaring” thesheet—that is, bringing the tensile ratio closer to 1.0.

[0087] Higher caliper at equivalent finished product cross-machinedirection tensile strength is illustrated by three examples presented inTable 3. For each example a common basesheet (identified above each dataset) was perforate embossed with a cross-machine direction and a machinedirection oriented pattern (Hollow Diamond is a machine directionoriented perforate emboss). Calipers reported herein are 8 sheetcalipers unless otherwise indicated. The sheets are stacked and thecaliper measurement taken about the central portion of the stack.Preferably, the test samples are conditioned in an atmosphere of23°±1.0° C. (73.4°±1.8° F.) at 50% relative humidity for at least about2 hours and then measured with a Thwing-Albert Model 89-II-JR or ProgageElectronic Thickness Tester with 2-in (50.8-mm) diameter anvils, 539±10grams dead weight load, and 0.231 in./sec descent rate. TABLE 3Increased Caliper at Equivalent CD Tensile Strength MD Dry CD Dry DryTensile Emboss Basis Wt. Caliper Tensile Tensile Ratio (perforate)(lbs/R) (mils) (g/3″) (g/3″) (MD/CD) Basesheet - undulatoryblade-creped, CWP basesheet with tensile ratio = 1.32 CD Quilt 28.8 1084773 4068 1.17 MD Quilt 28.8  78 6448 3880 1.66 Basesheet - undulatoryblade-creped, CWP basesheet with tensile ratio = 1.32 CD Quilt 29.5 1542902 2363 1.23 MD Quilt 29.5 120 5361 2410 2.22 Basesheet - undulatoryblade-creped, CWP basesheet with tensile ratio = 1.94 CD Oval 24.6  754805 2551 1.88 Hollow 24.1  56 5365 2364 2.27 Diamond

[0088] In each case, the cross-machine direction perforate embossedproduct displays enhanced caliper at equivalent cross-machine directiondry tensile strength relative to its machine direction perforateembossed counterpart. Also, the cross-machine direction perforateembossed product has a lower tensile ratio, while the machine directionperforate embossed product has a higher tensile ratio, when compared tothe corresponding basesheet.

[0089] The current invention further allows for a substantial reductionin base paper weight while maintaining the end product performance of ahigher basis weight product. As shown in Table 4, wherein the web isformed of recycled fibers, the lower basis weight cross-machinedirection perforate embossed towels achieved similar results to machinedirection perforate embossed toweling made with higher basis weights.TABLE 4 Performance Comparisons PRODUCT ID A B C D EMBOSS Hollow CDHollow CD Diamond Oval Diamond Oval (MD (CD (MD (CD Perforate)Perforate) Perforate) Perforate) BASIS WT(LBS/REAM) 24.1 22.2 31.3 28.9CALIPER 56 62 76 81 DRY MD TENSILE 5365 5057 5751 4144 (g/3″) DRY CDTENSILE 2364 2391 3664 3254 (g/3″) MD STRETCH (%) 7.6 8.1 8.8 10.1 CDSTRETCH (%) 6.3 6.1 5.5 5.3 WET MD CURED 1236 1418 1409 922 TENSILE(g/3″) WET CD CURED 519 597 776 641 TENSILE (g/3″) MacBeth 3100 72.372.6 73.3 73.4 BRIGHTNESS (%) SAT CAPACITY (g/m²⁾ 98 102 104 119 SINTECHMODULUS 215 163 232 162 BULK DENSITY 367 405 340 385 WET RESILENCY 0.7350.725 0.7 14 0.674 (RATIO)

[0090] In Table 4, two comparisons are shown. In the first comparison, a24.1 lbs/ream machine direction perforated web is compared with a 22.2lbs/ream cross-machine direction perforated web. Despite the basisweight difference of 1.9 lbs/ream, most of the web characteristics ofthe lower basis weight web are comparable to, if not better than, thoseof the higher basis weight web. For example, the caliper and the bulkdensity of the cross-machine direction perforated web are each about 10%higher than those of the machine direction perforated web. The wet anddry tensile strengths of the webs are comparable, while the Sintechmodulus of the cross-machine direction perforated web (i.e., the tensilestiffness of the web, where a lower number is preferred) is considerablyless than that of the machine direction perforated web. In the secondcomparison, similar results are achieved in the sense that comparabletensile ratios and physicals can be obtained with a lower basis weightweb. Paradoxically, consumer data indicates that the D product was ratedequivalent to the C product while the B product was at statisticalparity with the A product, but was possibly slightly less preferred thanthe A product.

[0091] The invention is further appreciated by reference to Table 5below which shows sheet properties, pre- and post-emboss. It is seenthat Examples I through P embossed in accordance with the invention,exhibit much less CD tensile loss than other products where similarcaliper gain is realized by embossing. TABLE 5 Pre- and Post-EmbossSheet Properties Emboss Sheet E Sheet F Sheet G 10M Hollow DiamondHollow Diamond % % % BS* FP** Change BS* FP** Change BS* FP** ChangeBasis Weight 26.1 26.1  0% 26.2 26.1  0% 25.7 26.2  2% (lbs/rm) Caliper(mils/8 40.9 54.3  33% 40.7 59.4  46% 38.0 58.5  54% sheets) Dry MDTensile 6938 5658 −18% 6904 4432 −36% 7297 5365 −26% (g/3″) Dry CDTensile 3516 2426 −31% 3560 2132 −40% 3457 2503 −28% (g/3″) MD Stretch(%) 4.8 5.9  25% 4.9 4.8  −2% 5.1 5.4  6% CD Stretch (%) 4.7 5.2  14%4.2 5.2  24% 4.0 5.2  30% MD TEA (mm- 2.8 2.3 −15% 2.8 1.4 −49% 3.0 2.0−33% gmm{circumflex over ( )}2) CD TEA (mm- 1.3 0.8 −38% 1.3 0.8 −34%1.2 1.0 −13% gm/mm{circumflex over ( )}2) Wet MD Cured 1249 1110 −11%1235 778 −37% 1530 1082 −29% Tensile (g/3″) sponge Wet CD Cured 614 445−27% 573 377 −34% 647 493 −24% Tensile (g/3″) sponge Wet MD Cured 1270932 −25% 1108 704 −36% 1306 904 −31% Tensile (g/3″) Finch Wet CD Cured628 396 −37% 550 355 −36% 653 450 −31% Tensile (g/3″) Finch WAR(seconds) 32 25 −16% 33 26 −20% 38 33 −11% (TAPPI) MacBeth 3100 91.291.3  0% 91.1 91.3  0% 91.4 L* UV Excluded MacBeth 3100 −1.3 −1.3  −6%−1.3 −1.2  −8% −1.5 A* UV Excluded MacBeth 3100 6.2 5.8  −6% 6.6 6.2 −6% 6.0 B* UV Excluded MacBeth 3100 71.7 72.4  1% 71.0 72.0  1% 72.3Brightness (%) UV Excluded MacBeth 3100 - 76.6 76.9  0% 76.3 76.4  0%76.8 Opacity (%) SAT Capacity 113 122  7% 117 135  15% 107 128  20%(g/m{circumflex over ( )}2) SAT Time 624 369 −41% 610 414 −32% 645 619 −4% (seconds) SAT Rate 0.0113 0.0116  2% 0.0122 0.0111  −9% 0.01050.0080 −24% (g/sec{circumflex over ( )}0.5) Sintech 263 181 −30% 273 164−40% 246 150 −39% Modulus Void Volume 366 366  0% 344 387  13% 324 401 24% Wt Inc (%) Wet Resiliency 0.847 0.728 −14% 0.831 0.707 −15% 0.7930.700 −12% Energy Ratio (Ratio) Wet Resiliency 0.853 0.784  −8% 0.8530.703 −18% 0.852 0.734 −14% Springback (Ratio) Wet Resiliency 3.20 3.19 0% 3.21 3.23  1% 3.19 3.21  1% Wet Comp Bulk (cm{circumflex over( )}3/g) Stack Height 5.29 (inches) Free-Standing 5.41 Stack Height(inches) Compressed 5.13 Stack Height (inches) Stack 5.20 Compression(%) Sheet Length 9.57 (inches) Sheet Width 9.35 (inches) Folded Sheet3.21 Width (inches) Folded Sheet 9.35 Length (inches) Emboss Sheet HSheet I (full step) Sheet J (full step) Hollow Diamond CD Oval CD Oval %% % BS* FP** Change BS* FP*** Change BS* FP** Change Basis Weight 23.924.1  1% 21.7 21.5  −1% 22.6 22.9  1% (lbs/rm) Caliper (mils/8 34.6 65.2 89% 34.9 59.9  72% 48.0 61.0  27% sheets) Dry MD Tensile 6003 4896 −19%6062 4578 −24% 7022 5639 −20% (g/3″) Dry CD Tensile 3215 1934 −40% 28472366 −17% 3604 3041 −16% (g/3″) MD Stretch (%) 8.0 7.6  −4% 10.5 10.0 −5% 5.6 6.1  8% CD Stretch (%) 4.2 5.6  33% 4.4 4.6  5% 5.8 6.8  18% MDTEA (mm- 4.3 2.5 −42% 5.2 3.1 −40% 3.6 2.5 −30% gmm{circumflex over( )}2) CD TEA (mm- 1.2 0.9 −26% 1.0 0.8 −18% 1.6 1.6  −8%gm/mm{circumflex over ( )}2) Wet MD Cured 1113 810 −26% 936 704 −25%1579 1294 −18% Tensile (g/3″) sponge Wet CD Cured 500 324 −35% 389 315−19% 818 699 −15% Tensile (g/3″) sponge Wet MD Cured 825 702  −6% 885612 −31% 1798 1165 −35% Tensile (g/3″) Finch Wet CD Cured 425 306 −28%405 282 −30% 955 662 −31% Tensile (g/3″) Finch WAR (seconds) 79 55 −30%114 113  −1% 61 59  −3% (TAPPI) MacBeth 3100 88.2 88.7  1% 87.8 88.0  0%89.6 90.0  0% L* UV Excluded MacBeth 3100 −1.0 −0.2 −85% −1.3 −0.6 −55%−1.3 −1.2  −5% A* UV Excluded MacBeth 3100 5.1 2.7 −47% 4.9 2.9 −40% 6.96.1 −11% B* UV Excluded MacBeth 3100 66.9 70.4  5% 66.3 68.7  4% 67.669.3  3% Brightness (%) UV Excluded MacBeth 3100 - 71.8 71.8  0% 74.383/0  0% 73.0 74.6  2% Opacity (%) SAT Capacity 95.8 141.4  47% 77.5113.9  47% 110.4 100.0  −9% (g/m{circumflex over ( )}2) SAT Time 868 579−31% 838 574 −32% 924 229 −75% (seconds) SAT Rate 0.0081 0.0053 −37%0.060 0.0067  11% 0.087 0.0060 −31% (g/sec{circumflex over ( )}0.5)Sintech 204 127 −37% 230 155 −33% 202 173 −14% Modulus Void Volume 376415  14% 341 373  9% 387 375  −3% Wt Inc (%) Wet Resiliency Energy Ratio(Ratio) Wet Resiliency Springback (Ratio) Wet Resiliency Wet Comp Bulk(cm{circumflex over ( )}3/g) Stack Height 5.30 5.00 5.36 (inches)Free-Standing 5.47 5.25 5.56 Stack Height (inches) Compressed 5.12 4.855.13 Stack Height (inches) Stack 6.39 7.62 7.81 Compression (%) SheetLength 9.45 9.55 9.57 (inches) Sheet Width 6.22 9.31 9.26 (inches)Folded Sheet 3.18 3.18 3.27 Width (inches) Folded Sheet 9.28 9.34 9.26Length (inches) Emboss Sheet K (half step) Sheet L (full step) Sheet M(full step) CD Oval CD Oval CD Oval % % BS* FP** Change BS* FP** ChangeBS* FP** Change Basis Weight 25.9 25.9  0% 25.9 26.2  1% 26.3 26.2  0%(lbs/rm) Caliper (mils/8 41.9 56.2  34% 41.9 56.5  35% 39.1 59.8  54%sheets) Dry MD Tensile 6323 5519 −13% 6323 5469 −14% 7274 5623 −23%(g/3″) Dry CD Tensile 3172 2668 −16% 3172 2747 −13% 3703 3005 −19%(g/3″) MD Stretch (%) 5.1 5.6  9% 5.1 5.7  10% 5.0 5.7  13% CD Stretch(%) 4.3 4.9  14% 4.3 4.7  10% 4.5 4.7  8% MD TEA (mm- 2.6 2.2 −18% 2.62.2 −17% 3.0 2.1 −31% gmm{circumflex over ( )}2) CD TEA (mm- 1.1 1.0 −7% 1.1 1.0  −7% 1.3 1.1 −17% gm/mm{circumflex over ( )}2) Wet MD Cured1080 930 −14% 1080 917 −15% 1239 975 −21% Tensile (g/3″) sponge Wet CDCured 549 446 −19% 549 440 −20% 598 492 −18% Tensile (g/3″) sponge WetMD Cured 892 855  −4% 892 809  −9% 1060 836 −21% Tensile (g/3″) FinchWet CD Cured 516 432 −16% 516 451 −13% 574 451 −21% Tensile (g/3″) FinchWAR (seconds) 22 25  12% 22 23  5% 46 38 −15% (TAPPI) MacBeth 3100 90.991.2  0% 90.9 91.1  0% 91.1 L* UV Excluded MacBeth 3100 −1.3 −1.3  −2%−1.3 −1.3  −2% −1.2 A* UV Excluded MacBeth 3100 6.3 6.2  −2% 6.3 6.2 −2% 5.4 B* UV Excluded MacBeth 3100 71.0 71.7  1% 71.0 71.6  1% 72.4Brightness (%) UV Excluded MacBeth 3100 - 75.9 76.5  1% 75.9 76.5  1%76.5 Opacity (%) SAT Capacity 121 133  9% 121 131  8% 115 138  21%(g/m{circumflex over ( )}2) SAT Time 759 796  5% 759 818  8% 798 853 14% (seconds) SAT Rate 0.014 0.015  10% 0.014 0.014  4% 0.0111 0.0092−22% (g/sec{circumflex over ( )}0.5) Sintech 275 222 −19% 275 228 −17%333 203 −38% Modulus Void Volume 357 379  6% 357 365  2% 331 361  9% WtInc (%) Wet Resiliency 0.737 0.676  −8% 0.737 0.671  −9% 0.743 0.698 −6% Energy Ratio (Ratio) Wet Resiliency 0.842 0.764  −9% 0.842 0.772 −8% 0.848 0.761 −10% Springhack (Ratio) Wet Resiliency 3.25 5.42  67%3.25 3.23  −1% 3.11 3.13  0% Wet Comp Bulk (cm{circumflex over ( )}3/g)Stack Height 5.19 5.20 5.25 (inches) Free-Standing 5.23 5.23 5.40 StackHeight (inches) Compressed 5.06 5.05 5.08 Stack Height (inches) Stack3.16 3.43 5.96 Compression (%) Sheet Length 9.58 9.53 9.47 (inches)Sheet Width 9.42 9.38 9.44 (inches) Folded Sheet 3.29 3.28 3.23 Width(inches) Folded Sheet 9.38 9.37 9.35 Length (inches) Emboss Sheet N(full step) Sheet O (full step) Sheet P (full step) CD Oval CD Oval CDOval % % % BS* FP** Change BS* FP** Change BS* FP** Change Basis Weight26.2 25.7  −2% 22.5 22.5  0% 24.3 24.1 −0.8% (lbs/rm) Caliper (mils/839.5 53.8  36% 41.0 58.3  42% 37.7 57.4 52.3% sheets) Dry MD Tensile7778 5712 −27% 6374 4322 −32% 5616 4831 −13.6% (g/3″) Dry CD Tensile4096 3196 −22% 3006 2234 −26% 3004 2452 −18.3% (g/3″) MD Stretch (%) 5.36.0  13% 3.6 3.9  8% 7.8 8.1 4.0% CD Stretch (%) 4.3 4.5  7% 4.7 4.9  4%4.1 4.2 3.7% MD TEA (mm- 3.4 2.2 −36% 2.0 1.2 −40% 3.5 2.7 −18.9%gmm{circumflex over ( )}2) CD TEA (mm- 1.5 1.2 −24% 1.1 0.8 −26% 0.9 0.7−20.3% gm/mm{circumflex over ( )}2) Wet MD Cured 1248 992 −21% 953 615−35% 986 751 −23.3% Tensile (g/3″) sponge Wet CD Cured 658 543 −17% 422291 −31% 432 363 −15.4% Tensile (g/3″) sponge Wet MD Cured 1180 908 −23%708 608 −14% 792 660 −14.4% Tensile (g/3″) Finch Wet CD Cured 602 508−13% 380 288 −24% 373 300 −19.1% Tensile (g/3″) Finch WAR (seconds) 4952  7% 67 46 −32% 75 68 −5.8% (TAPPI) MacBeth 3100 90.9 76.0 75.2 75.30.2% L* UV Excluded MacBeth 3100 −1.4 0.5 0.9 0.9 A* UV Excluded MacBeth3100 5.5 9.8 10.6 10.7 1.2% B* UV Excluded MacBeth 3100 72.0 41.5 39.940.0 0.3% Brightness (%) UV Excluded MacBeth 3100 - 76.0 88.1 86.4 87.00.7% Opacity (%) SAT Capacity 108 123  13% 105 122  16% 102.5 114.312.2% (g/m{circumflex over ( )}2) SAT Time 669 639  −4% 637 521 −18% 501344 −30.2% (seconds) SAT Rate 0.010 0.0085 −15% 0.0107 0.011  3% 0 0−32.7% (g/sec{circumflex over ( )}0.5) Sintech 298 157 −47% 232 200 −14%244.53 145.64 −39.1% Modulus Void Volume 312 369  18% 399 423  6% 350387 10.7% Wt Inc (%) Wet Resiliency 0.824 0.763  −7% 1 Energy Ratio(Ratio) Wet Resiliency 0.862 0.771 −11% 0.806 Springback (Ratio) WetResiliency 3.53 3.55  1% 2.867 Wet Comp Bulk (cm{circumflex over( )}3/g) Stack Height 5.17 5.26 (inches) Free-Standing 5.30 5.44 StackHeight (inches) Compressed 4.96 5.03 Stack Height (inches) Stack 6.517.43 Compression (%) Sheet Length 9.58 9.57 (inches) Sheet Width 9.329.31 (inches) Folded Sheet 9.31 3.25 Width (inches) Folded Sheet 3.239.31 Length (inches)

[0092] As will be appreciated from the foregoing, the CD embossingtechnique of the present invention is especially advantageous for use onbiaxially undulatory basesheet as described in U.S. Pat. No. 5,690,788,the disclosure of which is incorporated herein by reference anddescribed briefly below in connection with FIGS. 19 through 23.

[0093]FIG. 19 illustrates a papermachine wherein a machine chest 100,which may be compartmentalized, is used for preparing furnishes that aretreated with chemicals having different functionality depending on thecharacter of the various fibers used. This embodiment shows two headboxes thereby making it possible to produce a stratified product. Theproduct according to the present invention can be made with single ormultiple head boxes and regardless of the number of head boxes may bestratified or unstratified. The treated furnish is transported throughdifferent conduits 102 and 104, where they are delivered to the head box106, 108 (indicating an optionally compartmented headbox) of a crescentforming machine 110.

[0094]FIG. 19 shows a web-forming end or wet end with a liquid permeableforaminous support member 112 which may be of any conventionalconfiguration. Foraminous support member 112 may be constructed of anyof several known materials including photopolymer fabric, felt, fabric,or a synthetic filament woven mesh base with a very fine synthetic fiberbatt attached to the mesh base. The foraminous support member 112 issupported in a conventional manner on rolls, including breast roll 114and couch or pressing roll, 116.

[0095] Forming wire 118 is supported on rolls 120 and 122 which arepositioned relative to the breast roll 114 for pressing the wire 118 toconverage on the foraminous support member 112. The foraminous supportmember 112 and the wire 118 move in the same direction and at the samespeed which is in the direction of rotation of the breast roll 114. Thepressing wire 114 and the foraminous support member 112 converge at anupper surface of the forming roll 114 to form a wedge-shaped space ornip into which one or more jets of water or foamed liquid fiberdispersion (furnish) provided by single or multiple headboxes 106, 108is pressed between the pressing wire 118 and the foraminous supportmember 112 to force fluid through the wire 118 into a saveall 126 whereit is collected to reuse in the process.

[0096] The nascent web, W, formed in the process is carried by theforaminous support member 112 to the pressing roll 116 where the nascentweb, W, is transferred to the drum 130 of a Yankee dryer. Fluid ispressed from the web, W, by pressing roll 116 as the web is transferredto the drum 130 of a dryer where it is partially dried and preferablywet-creped by means of an undulatory creping blade 132. The wet-crepedweb is then transferred to an after-drying section 150 prior to beingcollected on a take-up roll 148. The drying section 150 may includethrough-air dryers, impingement dryers, can dryers, another Yankee dryerand the like as is well known in the art and discussed further below.

[0097] A pit 164 is provided for collecting water squeezed from thefurnish by the press roll 116. The water collected in pit 164 may becollected into a flow line 165 for separate processing to removesurfactant and fibers from the water and to permit recycling of thewater back to the papermaking machine 110.

[0098] An absorbent paper web can be made by dispersing fibers intoaqueous slurry and depositing the aqueous slurry onto the forming wireof a papermaking machine. Any suitable forming scheme might be used. Forexample, an extensive but non-exhaustive list includes a crescentformer, a C-wrap twin wire former, an S-wrap twin wire former, a suctionbreast roll former, a Fourdrinier former, or any art-recognized formingconfiguration. The forming fabric can be any suitable foraminous memberincluding single layer fabrics, double layer fabrics, triple layerfabrics, photopolymer fabrics, and the like. Non-exhaustive backgroundart in the forming fabric area includes U.S. Pat. Nos. 4,157,276;4,605,585; 4,161,195; 3,545,705; 3,549,742; 3,858,623; 4,041,989;4,071,050; 4,112,982; 4,149,571; 4,182,381; 4,184,519; 4,314,589;4,359,069; 4,376,455; 4,379,735; 4,453,573; 4,564,052; 4,592,395;4,611,639; 4,640,741; 4,709,732; 4,759,391; 4,759,976; 4,942,077;4,967,085; 4,998,568; 5,016,678; 5,054,525; 5,066,532; 5,098,519;5,103,874; 5,114,777; 5,167,261; 5,199,261; 5,199,467; 5,211,815;5,219,004; 5,245,025; 5,277,761; 5,328,565; and 5,379,808 all of whichare incorporated herein by reference in their entirety. One formingfabric particularly useful is Voith Fabrics Forming Fabric 2164 made byVoith Fabrics Corporation, Shreveport, La.

[0099] Foam-forming of the aqueous furnish on a forming wire or fabricmay be employed as a means for controlling the permeability or voidvolume of the sheet upon wet-creping. Suitable foam-forming techniquesare disclosed in U.S. Pat. No. 4,543,156 and Canadian Patent No.2,053,505, the disclosures of which are incorporated herein byreference.

[0100] The creping angle and blade geometry may be employed as means toinfluence the sheet properties. Referring to FIG. 20, the creping angleor pocket angle, α, is the angle that the creping rake surface 171 makeswith a tangent 172 to a Yankee dryer at the line of contact of thecreping blade 132 with the rotating cylinder 130 as in FIG. 19. So also,an angle γ is defined as the angle the blade body makes with tangent172, whereas the bevel angle of creping blade 132 is the angle surface171 defines with a perpendicular 174 to the blade body as shown in thediagram. Referring to FIG. 20, the creping angle is readily calculatedfrom the formula:

α=90+blade bevel angle−γ

[0101] for a conventional blade. These parameters vary over the crepingsurface of an undulatory blade as discussed herein.

[0102] In accordance with the present invention, creping of the paperfrom a Yankee dryer is carried out using an undulatory creping blade,such as that disclosed in U.S. Pat. No. 5,690,788, the disclosure ofwhich is incorporated by reference. Use of the undulatory crepe bladehas been shown to impart several advantages when used in production oftissue products. In general, tissue products creped using an undulatoryblade have higher caliper (thickness), increased CD stretch, and ahigher void volume than do comparable tissue products produced usingconventional crepe blades. All of these changes effected by use of theundulatory blade tend to correlate with improved softness perception ofthe tissue products. These blades, together with high-lignin pulps,cooperate to provide unexpected and, indeed, dramatic synergistic effectas discussed in connection with the examples below.

[0103]FIGS. 21A through 21D illustrate a portion of a preferredundulatory creping blade 190 useable in the practice of the presentinvention in which a relief surface extends indefinitely in length,typically exceeding 100 inches in length and often reaching over 26 feetin length to correspond to the width of the Yankee dryer on the largermodern papermachines. Flexible blades of the patented undulatory bladehaving indefinite length can suitably be placed on a spool and used onmachines employing a continuous creping system. In such cases the bladelength would be several times the width of the Yankee dryer. Incontrast, the height of the blade 190 is usually on the order of severalinches while the thickness of the body is usually on the order offractions of an inch.

[0104] As illustrated in FIGS. 21A through 21D, an undulatory cuttingedge 193 of the patented undulatory blade is defined by serrulations 196disposed along, and formed in, one edge of a surface 192 so as to definean undulatory engagement surface. Cutting edge 193 is preferablyconfigured and dimensioned so as to be in continuous undulatoryengagement with Yankee 130 when positioned as shown in FIG. 20, that is,the blade continuously contacts the Yankee cylinder in a sinuous linegenerally parallel to the axis of the Yankee cylinder. In particularlypreferred embodiments, there is a continuous undulatory engagementsurface 200 having a plurality of substantially colinear rectilinearelongate regions 202 adjacent a plurality of crescent shaped regions 204about a foot 206 located at the upper portion of the side 208 of theblade which is disposed adjacent the Yankee. Undulatory surface 200 isthus configured to be in continuous surface-to-surface contact over thewidth of a Yankee cylinder when in use as shown in FIGS. 19 and 20 in anundulatory or sinuous wave-like pattern.

[0105] The number of teeth per inch may be taken as the number ofelongate regions 202 per inch and the tooth depth is taken as theheight, H, of the groove indicated at 201 adjacent surface 208.

[0106] Several angles are used in order to describe the geometry of thecutting edge of the undulatory blade. To that end, the following termsare used:

[0107] Creping angle “α”—the angle between a rake surface 198 of theblade 190 and the plane tangent to the Yankee at the point ofintersection between the undulatory cutting edge 193 and the Yankee;

[0108] Axial rake angle “β”—the angle between the axis of the Yankee andthe undulatory cutting edge 193 which is the curve defined by theintersection of the surface of the Yankee with indented rake surface ofthe blade 190;

[0109] Relief angle “γ”—the angle between the relief surface 192 of theblade 190 and the plane tangent to the Yankee at the intersectionbetween the Yankee and the undulatory cutting edge 193, the relief anglemeasured along the flat portions of the present blade is equal to whatis commonly called “blade angle” or holder angle”, that is “γ” in FIG.20.

[0110] Quite obviously, the value of each of these angles will varydepending upon the precise location along the cutting edge at which itis to be determined. The remarkable results achieved with the undulatoryblades of the patented undulatory blade in the manufacture of theabsorbent paper products are due to those variations in these anglesalong the cutting edge. Accordingly, in many cases it will be convenientto denote the location at which each of these angles is determined by asubscript attached to the basic symbol for that angle. As noted in the'788 patent, the subscripts “f”, “c” and “m” refer to angles measured atthe rectilinear elongate regions, at the crescent shaped regions, andthe minima of the cutting edge, respectively. Accordingly, “γ_(f)”, therelief angle measured along the flat portions of the present blade, isequal to what is commonly called “blade angle” or “holder angle”. Ingeneral, it will be appreciated that the pocket angle α_(f) at therectilinear elongate regions is typically higher than the pocket angleα_(c) at the crescent shaped regions.

[0111] An undulatory creping blade may be used to produce a creped orrecreped web as shown in FIG. 21E comprising a biaxially undulatorycellulosic fibrous web 151 creped from a Yankee dryer 130 shown in FIGS.19 and 20, characterized by a reticulum of intersecting crepe bars 155,and undulations defining ridges 153 extending in the machine direction35 on the air side thereof, said crepe bars 155 extending transverselyin the cross-machine direction, the web 151 having furrows 157 betweenridges 153 on the air side as well as crests 159 disposed on the Yankeeside of the web opposite furrows 157 and sulcations 161 interspersedbetween crests 159 and opposite to ridges 153, wherein the spatialfrequency of said transversely extending crepe bars 155 is from about 10to about 150 crepe bars per inch, and the spatial frequency of saidlongitudinally extending ridges 153 is from about 4 to about 50 ridgesper inch. The distance between ridges 140 is taken as thecenter-to-center distance between adjacent ridges. This distance is theinverse of the frequency, F, of the machine direction ridges in thecross direction 37. For a product made with a creping blade with 12teeth per inch, the frequency, F, is 12 ridges/inch and the distance 140is {fraction (1/12)}″. It should be understood that strong calenderingof the sheet can significantly reduce the height of ridges 153, makingthem difficult to perceive by the eye, without loss of the beneficialeffects.

[0112] The crepe frequency count for a creped basesheet or product maybe measured with the aid of a microscope. The Leica Stereozoom.RTM. 4microscope has been found to be particularly suitable for thisprocedure. The sheet sample is placed on the microscope stage with itsYankee side up and the cross direction of the sheet vertical in thefield of view. Placing the sample over a black background improves thecrepe definition. During the procurement and mounting of the sample,care should be taken that the sample is not stretched. Using a totalmagnification of 18-20, the microscope is then focused on the sheet. Anillumination source is placed on either the right or left side of themicroscope stage, with the position of the source being adjusted so thatthe light from it strikes the sample at an angle of approximately 45degrees. It has been found that Leica or Nicholas Illuminators aresuitable light sources. After the sample has been mounted andilluminated, the crepe bars are counted by placing a scale horizontallyin the field of view and counting the crepe bars that touch the scaleover a one-half centimeter distance. This procedure is repeated at leasttwo times using different areas of the sample. The values obtained inthe counts are then averaged and multiplied by the appropriateconversion factor to obtain the crepe frequency in the desired unitlength.

[0113] It should be noted that the thickness of the portion of web 151between longitudinally extending crests 159 and furrows 157 will on theaverage typically be bout 5% greater than the thickness of portions ofweb 151 between ridges 153 and sulcations 161. Suitably, the portions ofweb 151 adjacent longitudinally extending ridges 153 (on the air side)are about from about 1% to about 7% thinner than the thickness of theportion of web 151 adjacent to furrows 157 as defined on the air side ofweb 151.

[0114] The height of ridges 153 correlates with the tooth depth, H,formed in undulatory creping blade 190. At a tooth depth of about 0.010inches, the ridge height is usually from about 0.0007 to about 0.003inches for sheets having a basis weight of 14-19 pounds per ream. Atdouble the depth, the ridge height increases to 0.005 to 0.008 inches.At tooth depths of about 0.030 inches, the ridge height is about 0.010to 0.013 inches. At higher undulatory depth, the height of ridges 153may not increase and could in fact decrease. The height of ridges 153also depends on the basis weight of the sheet and strength of the sheet.

[0115] Advantageously, the average thickness of the portion of web 151adjoining crests 159 is significantly greater than the thickness of theportions of web 151 adjoining sulcations 161; thus, the density of theportion of web 151 adjacent crests 159 can be less than the density ofthe portion of web 151 adjacent sulcations 161. The process of thepresent invention produces a web having a specific caliper of from about2 to about 8 mils per 8 sheets per pound of basis weight. The usualbasis weight of web 151 is from about 7 to about 35 lbs/3000 sq. ft.ream.

[0116] Suitably, when web 151 is calendered, the specific caliper of web151 is from about 2.0 to about 6.0 mils per 8 sheets per pound of basisweight and the basis weight of said web is from about 7 to about 35lbs/3000 sq. ft. ream.

[0117] While the products of the invention may be made by way of adry-crepe process, a wet crepe process is preferred in some embodiments,particularly with respect to single-ply towel in some cases. When awet-crepe process is employed, after-drying section 150 may include animpingement air dryer, a through-air dryer, a Yankee dryer or aplurality of can dryers. Impingement-air dryers are disclosed in thefollowing patents and applications, the disclosure of which isincorporated herein by reference:

[0118] U.S. Pat. No. 5,865,955 of Ilvespaaet et al.

[0119] U.S. Pat. No. 5,968,590 of Ahonen et al.

[0120] U.S. Pat. No. 6,001,421 of Ahonen et al.

[0121] U.S. Pat. No. 6,119,362 of Sundqvist et al.

[0122] U.S. patent application Ser. No. 09/733,172, entitled “Wet Crepe,Impingement-Air Dry Process for Making Absorbent Sheet”, now U.S. Pat.No. 6,432,267 (Attorney Docket No. 2236;

[0123] (FJ-99-33).

[0124] When an impingement-air after dryer is used, after drying section150 of FIG. 19 may have the configuration shown in FIG. 22.

[0125] There is shown in FIG. 22 an impingement air dry apparatus 150useful in connection with the present invention. The web is creped offof a Yankee dryer, such as Yankee dryer 130 of FIG. 19 utilizing acreping blade 132. The web, W, is aerodynamically stabilized over anopen draw utilizing an air foil 220 as generally described in U.S. Pat.No. 5,891,309 to Page et al., the disclosure of which is incorporatedherein by reference. Following a transfer roll 222, web, W, is disposedon a transfer fabric 224 and subjected to wet shaping by way of anoptional blow box 226 and vacuum shoe 228. The particular conditions andimpression fabric selected depend on the product desired and may includeconditions and fabrics described above or those described or shown inone or more of: U.S. Pat. No. 5,510,002 to Hermans et al.; U.S. Pat. No.4,529,480 of Trokhan; U.S. Pat. No. 4,102,737 of Morton and U.S. Pat.No. 3,994,771 to Morgan, Jr. et al., the disclosures of which are herebyincorporated by reference into this section.

[0126] After wet shaping, web, W, is transferred over vacuum roll 230impingement air-dry system in the machine direction 35 as shown. Theapparatus of FIG. 22 generally includes a pair of drilled hollowcylinders 232, 234, a vacuum roll 236 therebetween as well as a hood 238equipped with nozzles and air returns. In connection with FIG. 22, itshould be noted that transfer of a web, W, over an open draw needs to bestabilized at high speeds. Rather than use an impingement-air dryer,after-dryer section 150 of FIG. 22 may include instead of cylinders 232,234 of a throughdrying unit as is well known in the art and described inU.S. Pat. No. 3,432,936 to Cole et al., the disclosure of which isincorporated herein by reference.

[0127] Yet another after-drying section is disclosed in U.S. Pat. No.5,851,353 which may likewise be employed in a wet-creped process usingthe apparatus of FIG. 19.

[0128] Still yet another after-drying section 150 is illustratedschematically in FIG. 23. After creping from the Yankee cylinder theweb, W, is deposited on an after-dryer felt 240 which travels in machinedirection 35 and forms an endless loop about a plurality of after-dryerfelt rolls such as rolls 242, 244 and a plurality of after-dryer drumssuch as drums (sometimes referred to as cans) 246, 248 and 250.

[0129] A second felt 252 likewise forms an endless loop about aplurality of after-dryer drums and rollers as shown. The various drumsare arranged in two rows and the web is dried as it travels over thedrums of both rows and between rows as shown in the diagram. Felt 252carries web, W, from drum 254 to drum 256, from which web, W, may befurther processed or wound up on a take-up reel 258.

[0130] Referring to FIG. 24, there is shown schematically a portion ofan embossed sheet 300 with a plurality of ridges 302 extending in themachine direction 35 whose centerlines are indicated by the dashedlines, and wherein the center-to-center distance of adjacent ridges isindicated at 140. The frequency, F, of the ridges is the reciprocal ofthis distance; that is, ridges per inch. For example, if the distancebetween ridges is {fraction (1/12)}″, the frequency, F, is 12. The sheethas a surface 304 provided with a plurality of perforate embossments 306which are formed by embossing rolls having CD oval elements configuredgenerally as shown in FIGS. 3A-3D.

[0131] Embossments 306 extend in cross-machine direction 37 a distance,L′, which is typically less than the cross direction length of theembossing elements at their base, depending on the angle of the outeredges of the embossing elements and the engagement of the rolls. Notethat embossments 306 are spaced a lateral distance, D′, whichcorresponds roughly to the lateral distance between embossing elements;however, the dimensions may be different depending upon the engagementand geometry of the elements. The distance, D′, is also measured alongCD 37 in cases where the embossments are offset.

[0132] While the invention has been illustrated in connection withnumerous examples and embodiments, variations within the spirit andscope of the invention, set forth in the appended claims, will bereadily apparent to those of skill in the art.

What is claimed is:
 1. A method of embossing an absorbent web with anundulatory structure extending in the machine direction comprising:providing a web with a plurality of ridges extending in its machinedirection to an embossing station; wherein the plurality of ridgesextending in the machine direction of the web occur at a frequency, F,across the web; and embossing the web at the embossing station between afirst and second embossing roll, at least one of which rolls is providedwith a plurality of embossing elements and wherein the rolls are therebyconfigured to define therebetween a plurality of embossing nips; whereinat least a portion of the nips defined by the embossing rolls aresubstantially oriented in a cross-machine direction with respect to theweb and have a cross direction length, L, wherein the product F×L isfrom about 0.1 to about
 5. 2. The method according to claim 1, whereinthe product F×L is from about 0.2 to about
 3. 3. The method according toclaim 2, wherein the product F×L is from about 0.3 to about
 2. 4. Themethod according to claim 2, wherein the product F×L is from about 0.5to about 1.5.
 5. The method according to claim 1, wherein substantiallyall of the nips defined by the embossing rolls are substantiallyoriented in the cross direction.
 6. The method according to claim 1,wherein the embossing nips oriented in the cross direction compriseperforate embossing nips.
 7. The method according to claim 1, wherein atleast a portion of the embossing elements are male elements that aresubstantially oval shaped.
 8. The method according to claim 1, whereinat least a portion of the embossing elements are male elements that aresubstantially hexagonal shaped.
 9. The method according to claim 1,wherein at least a portion of the embossing elements are male elementsthat are substantially rectangular shaped.
 10. The method according toclaim 1, wherein the cross-machine direction oriented nips defined bythe embossing rolls are at an angle of from about 60° to about 120° fromthe machine direction.
 11. The method according to claim 1, wherein thecross-machine direction oriented nips defined by the embossing rolls areat an angle of from about 85° to about 95° from the machine direction.12. The method according to claim 1, wherein at least a portion of theembossing elements are male elements having a height of at least about15 mils.
 13. The method according to claim 12, wherein at least aportion of the embossing elements are male elements having a height ofat least about 30 mils.
 14. The method according to claim 1, wherein thecross-machine direction oriented nips are defined by embossing elementswhich are in full-step alignment.
 15. The method according to claim 1,wherein the cross-machine direction oriented nips are defined byembossing elements which are in half-step alignment.
 16. The methodaccording to claim 1, wherein the cross-machine direction oriented nipsare defined by embossing elements which are in quarter-step alignment.17. The method according to claim 1, wherein the cross-directionoriented embossing nips are defined by embossing elements on opposedembossing rolls and where the embossing element engagement is at leastabout 15 mils.
 18. The method according to claim 17, wherein thecross-direction oriented embossing nips are defined by embossingelements on opposed embossing rolls and where the embossing elementengagement is from about 16 to about 32 mils.
 19. The method accordingto claim 1, wherein the cross-machine direction oriented nips aredefined by embossing elements which have angled sidewalls, wherein thesidewalls have an angle of less than about 20°.
 20. The method accordingto claim 1, wherein at least a portion of the embossing elements have aheight of at least about 30 mils wherein the cross-direction orientedembossing nips are defined by embossing elements on opposed embossingrolls and where the engagement of opposed elements is at least about 15mils.
 21. The method according to claim 1, wherein at least a portion ofthe embossing elements have a height of at least about 30 mils whereinthe cross-direction oriented embossing nips are defined by embossingelements on opposed embossing rolls and where the engagement of opposedelements is at least about 24 mils.
 22. The method according to claim 1,wherein the web is a creped web prepared with an undulatory crepingblade, having a biaxially undulatory structure with crepe bars extendingin the cross direction and ridges extending in the machine direction.23. The method according to claim 22, wherein the web has from about 4to about 50 ridges per inch extending in the machine direction.
 24. Themethod according to claim 23, wherein the web has from about 8 to about25 ridges per inch extending in the machine direction.
 25. The methodaccording to claim 24, wherein the web has from about 10 to about 16ridges per inch extending in the machine direction.
 26. The methodaccording to claim 21, wherein the web has from about 4 to about 50ridges per inch extending in the machine direction and from about 10 toabout 150 crepe bars per inch extending in the cross-machine directionof the web.
 27. The method according to claim 1, wherein the embossingnips oriented in the cross-machine direction comprise perforateembossing nips and the embossing step is operative to reduce the drytensile ratio of the web.
 28. The method according to claim 1, whereinthe embossing nips comprise perforate embossing nips and the process ofembossing the web is operative to reduce the wet tensile ratio of theweb.
 29. The method according to claim 1, wherein at least a portion ofthe embossing nips are perforate embossing nips and wherein the processof embossing the web is operative to increase the transluminance ratioof the web.
 30. The method according to claim 1, operative to reduce theMD dry tensile strength of the web by less than about 15%.
 31. Themethod according to claim 30, operative to reduce the MD dry tensilestrength of the web by at least about 10%.
 32. The method according toclaim 1, operative to reduce the MD dry tensile strength of the web byfrom about 35% to about 65%.
 33. The method according to claim 1,operative to reduce the CD dry tensile strength by less than about 30%.34. The method according to claim 32, operative to reduce the CD drytensile strength by less than about 25%.
 35. The method according toclaim 33, operative to reduce the CD dry tensile strength by less thanabout 20%.
 36. The method according to claim 34, operative to reduce theCD dry tensile strength by less than about 15%.
 37. The method accordingto claim 1, operative to impart a caliper gain of at least about 15%.38. The method according to claim 36, operative to impart a caliper gainof at least about 20%.
 39. The method according to claim 37, operativeto impart a caliper gain of at least about 25%.
 40. The method accordingto claim 38, operative to impart a caliper gain of at least about 30%.41. The method according to claim 39, operative to impart a caliper gainof at least about 40%.
 42. A method of embossing an absorbent web withan undulatory structure extending in the machine direction comprising:providing a web with a plurality of ridges extending in its machinedirection to an embossing station; wherein the plurality of ridgesextending the machine direction of the web occur at a frequency, F,across the web; and embossing the web at the embossing station between afirst and second embossing roll, at least one of which rolls is providedwith a plurality of embossing elements and the rolls are therebyconfigured to define therebetween a plurality of embossing nips, whereinat least a portion of the nips defined by the embossing rolls aresubstantially oriented in the cross-machine direction, having a crossdirection length, L, and are laterally spaced at a distance, D, with theproviso that: (a) the product F×L is between about 0.1 and about 5 or(b) the product F×D is between about 0.1 and about
 5. 43. The methodaccording to claim 42, wherein the product F×L is from about 0.2 toabout
 3. 44. The method according to claim 42, wherein the product F×Dis from about 0.2 to about
 3. 45. The method according to claim 43,wherein substantially all of the nips defined by the embossing rolls aresubstantially oriented in the cross-machine direction.
 46. The methodaccording to claim 45, wherein the embossing nips oriented in thecross-machine direction comprise perforate embossing nips.
 47. Themethod according to claim 46, wherein at least a portion of theembossing elements are male elements that are substantially oval shaped.48. The method according to claim 42, wherein the web is a creped webprepared with an undulatory creping blade, having a biaxially undulatorystructure with crepe bars extending in the cross-machine direction andridges extending in the machine direction.
 49. The method according toclaim 48, wherein the web has from about 4 to about 50 ridges per inchextending in the machine direction.
 50. The method according to claim49, wherein the web has from about 8 to about 25 ridges per inchextending in the machine direction.
 51. The method according to claim50, wherein the web has from about 10 to about 16 ridges per inchextending in the machine direction.
 52. The method according to claim48, wherein the web has from about 4 to about 50 ridges per inchextending in the machine direction and from about 10 to about 150 crepebars per inch extending in the cross-machine direction.
 53. The methodaccording to claim 42, wherein the embossing nips comprise perforateembossing nips and wherein the process of embossing the web is operativeto reduce the dry tensile ratio of the web.
 54. The method according toclaim 42, wherein the embossing nips comprise perforate embossing nipsand wherein the process of embossing the web is operative to reduce thewet tensile ratio of the web.
 55. The method according to claim 42,wherein the embossing nips comprise perforate embossing nips and theprocess of embossing the web is operative to increase the transluminanceratio of the web.
 56. An embossed absorbent web having an undulatorystructure and a plurality of perforate embossments wherein theundulatory structure of the web comprises a plurality of ridgesextending in the machine direction of the web occurring at a frequency,F, across the web and at least a portion of the perforate embossments:(i) extend substantially in the cross-machine direction; and (ii) theperforate embossments extending in the cross-machine direction extend inthe cross-machine direction a distance, L′; and (iii) the perforateembossments extending in the cross-machine direction are laterallyspaced from adjacent perforate embossments extending in thecross-machine direction a distance, D′; with the proviso that: (a) theproduct F×L′ is between about 0.1 and about 5 or (b) the product F×D′ isbetween about 0.1 and about
 5. 57. The embossed absorbent web accordingto claim 56, wherein the web has a biaxially undulatory structure. 58.The embossed absorbent web according to claim 57, wherein the web has adry tensile ratio of less than about 1.2.
 59. The embossed absorbent webaccording to claim 57, wherein the web has a transluminance ratio of atleast about 1.005.
 60. The embossed absorbent web according to claim 59,having a transluminance ratio of at least about 1.01.
 61. The embossedabsorbent web according to claim 56, wherein the product F×L′ is fromabout 0.2 to about
 3. 62. The embossed absorbent web according to claim61, wherein the product F×L′ is from about 0.3 to about
 2. 63. Theembossed absorbent web according to claim 56, wherein the product F×D′is from about 0.2 to about
 3. 64. The embossed absorbent web accordingto claim 56, wherein substantially all of the embossments aresubstantially oriented in the cross-machine direction.
 65. The embossedabsorbent web according to claim 57, wherein the web has from about 4 toabout 50 ridges per inch extending in the machine direction.
 66. Theembossed absorbent web according to claim 65, wherein the web has fromabout 8 to about 25 ridges per inch extending in the machine direction.67. The embossed absorbent web according to claim 66, wherein the webhas from about 10 to about 16 ridges per inch extending in the machinedirection.
 68. The embossed absorbent sheet according to claim 67,wherein the web has from about 10 to about 50 ridges per inch extendingin the machine direction and from about 10 to about 150 crepe bars perinch extending in the cross-machine direction.